Method and apparatus for dilatation catheterization

ABSTRACT

Apparatus and method is disclosed for facilitating balloon catheter exchange in angioplasty procedures. A guide catheter allows the balloon catheter to be inserted into the subject to a region near a treatment region within the vascular system. A fluid source is provided for selectively inflating the balloon. A passageway in the catheter body that extends through the catheter balloon opens into the blood vessel via a sideport. A guidewire passageway extends through a distal most part of the catheter body to allow a guidewire to be inserted into the sideport and routed out the catheter body through a distal opening.

TECHNICAL FIELD

This invention relates generally to the field of catheterization, andmore specifically to new apparatus and method for facilitating balloonexchange during dilatation procedures such as angioplasty.

BACKGROUND ART

Catheterization procedures are well known for diagnosis and therapy oflesions in the cardiovascular system. One such procedure is angioplastywhich reduces the damaging effects of vascular plaque blockage orconstriction in blood vessels.

In an angioplasty procedure, an expandable balloon is introduced intothe patient's arterial system and advanced until it is positioned in theregion of the blockage or constriction. Once so positioned, the balloonis expanded by filling it with a liquid. In successful procedures, theexpandable balloon presses outwardly against the walls of the artery andexpands the artery to a degree to which the artery is either partiallyor totally re-opened to blood flow.

A typical angioplasty procedure, and components used in practicing theprocedure, are now described.

Prior to initiating the angioplasty procedure, a guiding catheter isplaced typically via the femoral artery into the aorta and its tip isengaged into the coronary arteries which branch from the aorta. Thisentrance into the coronary artery is called the ostium. Once placed, theguiding catheter acts as a conduit to access the coronary arteries witha balloon guidewire and balloon catheter. The guiding catheter is aportion of plastic tubing having a length of about 95 centimeters, aninside diameter of about 0.08 inches, and an outside diameter of about2.5 millimeters.

The physician positions a balloon catheter within the patient with theaid of a guidewire. The guidewire is a piece of elongated wire,approximately 175 centimeters in length, and about 0.010-0.018 inches indiameter. The distal tip of the guidewire can be shaped to form a "J"configuration. This "J" shape allows the physician to steer the wire bytwisting the proximal extremity of the guidewire while advancing orretracting the guidewire.

The balloon catheter is an elongated flexible member having a balloonlocated near its distal end. In a so called "Over-the-Wire" cathetersystem one longitudinal opening through the catheter defines a sleevethrough which the balloon guidewire can be passed. A second longitudinalpassage in the catheter defines a conduit communicating with theinterior of the balloon and through which inflation fluid can beinjected to inflate the balloon.

Among the types of balloon catheters is one of a type in which the twolongitudinal passages are generally side by side and parallel. Inanother type of balloon catheter, the two longitudinal passages areco-axial. In this latter type, the balloon guidewire is passed down theinner passage and the inflation fluid is injected into the balloon viathe outer passage.

Balloon catheters, as well as associated apparatus and method for use inangioplasty, are described in U.S. Pat. No. 5,040,548, issued on Aug.20, 1991, to Yock, and U.S. Pat. No. 4,762,129, issued on Aug. 8, 1988.Each of these issued U.S. patents is hereby expressly incorporated byreference.

Using the over-the-wire insertion technique, the physician passes theballoon guidewire through the guidewire passage in the balloon catheter,leaving a portion of the balloon guidewire extending from the distal endof the balloon catheter and also a portion extending from its proximalend.

This assembly is then inserted into the proximal end of the guidingcatheter, distal end first. The assembly is inserted until the balloonwhich is attached near the distal end of the balloon catheter is nearthe distal end of the guiding catheter. At this point, the physician,while maintaining the balloon catheter stationary, pushes on the balloonguidewire to advance it outwardly from the distal end of the guidingcatheter.

The balloon guidewire can be steered by appropriate twisting movement bythe physician. The physician steers the guidewire into the chosen one ofthe coronary arteries, and advances it until it reaches a location ofconstriction which the physician desires to re-open. Carefully, thephysician eases the guidewire through the region of restriction until aportion of the guidewire is on the opposite side of the constriction,relative to the guiding catheter.

With the balloon guidewire held stationary, the physician then advancesthe balloon catheter. The distal end of the balloon catheter, as it isadvanced, will, of course, follow the balloon guidewire which is alreadyin place.

The physician continues to advance the balloon until it is located inthe region of constriction of the artery. With the balloon and itsassociated catheter held stationary, inflation fluid is injected intothe conduit which communicates with the balloon, causing it to inflate.Inflation of the balloon expands the walls of the artery in the regionof constriction and, in successful procedures, re-opens the artery tosufficient blood flow.

Arteries vary in size, and therefore balloon catheters having balloonsof different sizes are provided for the physician's selection. Theseballoons, when inflated, range from about 1.5 millimeters to about 4millimeters in diameter.

Sometimes, it is necessary for the physician to use more than oneballoon to open an artery. Sometimes, the chosen balloon is too large tobe advanced into the constricted area. In other instances, the firstchosen balloon size, even when inflated, is not large enough to open theconstricted area to the degree desired. In such cases, it is necessaryto exchange one balloon for another during the same angioplastyprocedure.

In order to accomplish this exchange, the guidewire is left in place,and the balloon catheter is withdrawn entirely from the guiding catheteruntil it is completely disengaged from the guidewire. A new ballooncatheter, having a different sized balloon, is then re-inserted over theguidewire and advanced back to the location of the constricted area,where it is used to effect the desired result.

Once the guidewire has been inserted through the constricted area, it isdesirable to leave the guidewire in place for the entire angioplastyprocedure; even during exchanges of balloons. The reason for this isthat, when a foreign object, such as the guidewire, is introduced intoan artery, the artery walls sometimes go into spasm, and constrictgenerally along a substantial portion of its length. If the artery tendsto contract in this way, removal of the guidewire while the artery is socontracted will sometimes render it virtually impossible to re-insertthe guidewire through the contracted artery.

Additional prior art patents relating to balloon catheters are U.S. Pat.Nos. 4,762,129 to Bonzel, 5,098,381 to Schneider, 5,049,132 to Shafferet al, and 5,315,747 to Solar and published PCT applications WO 92/17236to Tartaglino et al and WO 92/20397 to Jung.

The Bonzel '381 patent concerns a so-called "rapid exchange" guidewirearrangement. Using such an arrangement the guidewire can be inserted andproperly positioned before the catheter is inserted into the guidecatheter.

It is a general object of the present invention to provide apparatus andmethod for facilitating introduction and exchange of balloons inangioplasty procedures.

DESCRIPTION OF THE INVENTION

The apparatus and method of the present invention concern a cathetersystem that includes a balloon catheter that can be positioned relativeto a treatment region of a subject's vascular system. The system alsoincludes a tubular guiding catheter sized for insertion into thevascular system of a subject to help position the balloon catheter. Anelongated guidewire longer than the tubular guiding catheter is pushedthrough the balloon catheter and is used in positioning the ballooncatheter after the balloon is pushed through the guide catheter.

A preferred balloon catheter constructed in accordance with the presentinvention includes an elongated catheter body and an inflatable catheterballoon coupled to the elongated catheter body near a distal end of thecatheter body. The catheter body defines a conduit for transmittingfluid from outside the subject through the catheter body into aninterior of the catheter balloon once the balloon is positioned relativeto the treatment region. The catheter body also defines a longitudinalpassageway that extends through the catheter balloon to a sideport inthe catheter body where the longitudinal passageway opens outwardly intothe blood vessel at a location distal to the balloon. A catheter bodysection distal of the balloon defines a guidewire passage that opensinto the blood vessel via the sideport and extends through the bodysection to a distal opening spaced from the sideport. A source ofinflation fluid is coupled to the catheter body for injecting fluidthrough the conduit to inflate the catheter balloon.

In accordance with two different disclosed embodiments of the inventionthe catheter balloon is a dilation balloon used to compress regions ofthe inner wall linings of a blood vessel. In accordance with one ofthese two embodiments the catheter is a perfusion catheter which allowsblood to flow through the catheter while the balloon is inflated andpressing against the inner lining of a blood vessel.

The structure of the disclosed balloon catheter enhances an ability toposition the balloon relative the treatment region of the subject. Thisand other objects, advantages and features of alternate embodiments ofthe invention are described in conjunction with the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an elevational view, partly in cross-section, illustrating aprior art balloon catheter system;

FIG. 2 is a sectional view of a catheter constructed in accordance withthe present invention;

FIG. 2A is an enlarged sectional view of the FIG. 2 catheter;

FIG. 3 is a view of the catheter as seen from the plane 3--3 of FIG. 2A;

FIG. 4 is a view of the catheter as seen from the plane 4--4 of FIG. 2A;

FIG. 5 is a sectional view of an alternate catheter constructed inaccordance with the present invention;

FIG. 5A is an enlarged sectional view of the FIG. 5 catheter; and

FIG. 6 is a sectional view as seen from the plane 6--6 of FIG. 5A.

BEST MODE FOR CARRYING OUT THE INVENTION

FIG. 1 shows the relevant portions of a system for positioning a ballooncatheter in relation to a treatment region. A guiding catheter 10 thathas been positioned within a patient subject's arterial system asdescribed above.

A balloon guidewire 12 is also illustrated. The balloon guidewire 12extends outwardly from a distal end of a balloon catheter 20 at atreatment region of the subject.

The balloon catheter 20 is illustrated with the balloon guidewire 12passing through a longitudinal passage extending through the ballooncatheter. The balloon catheter 20 of FIG. 1 is of the type wherein thelongitudinal passage for accommodating the balloon guidewire is centraland surrounded by a second co-axial passage for transmitting inflationfluid to a balloon 22.

The catheter balloon 22 is inflated by the injection of inflation fluidinto an inflation port 24 to expand outwardly to contact and imposeoutward pressure on the inner walls of a blood vessel in which theballoon has been positioned. Preferably, the inflation fluid is a knowntype of radiopaque liquid. The radiopaque nature of the liquid permitsthe configuration of the balloon 22 to be imaged by known apparatus andviewed by the physician on a continuous real time basis. The ballooncatheter is made of an extrusion of known relatively flexible plastic,such as nylon. The same is true of the guiding catheter.

It is to be understood that, as an alternative to the balloon catheterconstruction shown in FIG. 1, the balloon catheter may be of anotherknown configuration in which the longitudinal passages extending throughthe balloon catheter are not co-axial. In such an alternativeembodiment, the longitudinal passages through the balloon catheter areside by side and substantially parallel.

By pushing on the proximal end of the balloon catheter an attendingphysician can advance the balloon catheter and its associated balloon 22all the way through the guiding catheter 10 and out a distal end of theguiding catheter, from which the balloon catheter and balloon will trackthe balloon guidewire until the balloon reaches a treatment region.

When it is desired to inflate the balloon 22, inflation fluid is forcedunder pressure into the infusion port 24 of the balloon catheter byknown means, such as a syringe.

FIG. 1 illustrates a situation in which the physician has advanced theballoon catheter to the point at which the balloon 22 attached to theend of the balloon catheter, has exited the distal end of the guidingcatheter 10. It is to be understood that the balloon 22 is locatedwithin an artery of the patient, which artery is not shown. The balloonguidewire 12 is pre-located within the patient's artery and extends pastthe area of blockage or constriction.

FIGS. 2, 2A, 3 and 4 depict a balloon catheter 110 constructed inaccordance with one embodiment of the invention. The catheter 110 isplaced within a subject blood vessel 111 for treatment of a lesion Lwithin the vessel by applying a force of compression against the lesionL.

The catheter 110 includes an elongated catheter body 112 and aninflatable catheter balloon 114 coupled to the elongated catheter body112 near a distal end of said catheter body. The catheter body defines alongitudinal passageway 116 that extends through the catheter balloon toa sideport 120 in the catheter body that opens outwardly from a sidewallof the catheter body into a region 122 within a blood vessel adjacentthe sideport 120.

The catheter body also has a body section 130 distal of the balloon 114having a guidewire passage 132 that opens into the region 122 within theblood vessel near the sideport 120. The guidewire passage 132 alsoextends through the body section 130 to a distal opening 134 spaced fromthe sideport 120. The catheter body 112 also has a conduit or passageway140 for transmitting fluid from outside the subject through the catheterbody into an interior of the catheter balloon once the balloon 114 isproperly positioned relative to the lesion L.

The catheter shown in FIG. 2 includes a dilatation balloon 114. Such aballoon is fused around the circumferential extent of the catheter body112 at two spaced apart locations 142, 144 by heat fusing techniquesknown in the art. Midway between the spaced locations 142, 144 thecatheter body includes an opening 150 that opens outwardly from thepassageway 140 into the interior of the balloon 114. As seen in FIG. 2the passageway 140 extends outside the subject through the catheter bodyto a fitting 152 having a side port 154 for injecting fluid into thecatheter body through the passageway 140. Once the balloon has beenpositioned in bridging relation with the lesion L, the fluid is forcedinto the catheter to inflate the balloon and compress the lesion.

The catheter can be positioned using either the "over-the-wire" or the"rapid exchange" technique where the guidewire does not pass through theproximal portion of the catheter body 112. In an over the wire procedurethe guidewire enters the fitting 152 by a proximal port 160 having athreaded connector portion 162. The guidewire extends through apassageway 166 in the fitting 152 to the passageway 116 in the catheterbody. The guidewire 12 extends through the passageway 116, past thesideport 120, through the distal body portion passageway 132 and out thedistal opening 134.

When used in the "rapid exchange" mode of catheter placement, theguidewire passes through the sideport 120. The guidewire is first pushedthrough an appropriately positioned guide catheter until the distal endof the guidewire exits the guide catheter. The guidewire is then guidedby the physician into and through the region of an obstruction. Outsidethe subject the physician then pushes the distal opening 134 of thecatheter over the guidewire's proximal end and pushes until theguidewire exits the distal portion of the catheter body through thesideport 120. Since the guidewire is already properly positionedrelative to the lesion L, the catheter can be pushed along the guidewireto exit the guide catheter and the balloon brought into bridgingrelation with the lesion L.

Using this alternate guidewire configuration the catheter 110 can alsobe withdrawn from the guide catheter 10 without disturbing the positionof the guidewire 12 and a different catheter routed over the guidewireto the treatment region. In this embodiment the body passageway 116 isused to insert a stiffening mandrel 170. The stiffening mandrel 170 hasa ramp 172 at an enlarged distal end 174 that closes off the passageway116 to prevent the guidewire from entering the passageway 116 as thecatheter is pushed over the proximal end of the guidewire. Thepushability and flexibility of the catheter can be controlled by controlof the stiffness of the stiffening mandrel 170. A leur fitting 176 isattached to the proximal end of the mandrel. With the leur fitting 176attached to the threaded connector portion 162 of the fitting 152 themandrel 170 is positioned with respect to the catheter to close off theport 120.

ALTERNATE EMBODIMENT

FIGS. 5, 5A and 6 illustrate an alternate embodiment of a catheter 210constructed in accordance with the invention. The catheter 210 includesan elongated catheter body 212 and an inflatable catheter balloon 214coupled to the elongated catheter body 212 near a distal end of thecatheter body. The catheter body defines a longitudinal passageway 216that extends through the catheter balloon to a sideport 220 in thecatheter body that opens outwardly into a region 222 within a bloodvessel 211 adjacent the sideport 220. The passageway is most preferablyconstructed from a tube of plastic material used to construct catheterbodies such as nylon.

The catheter body also has a body section 230 distal of the balloon 214having a guidewire passage 232 that opens into the region 222 within theblood vessel near the sideport 220. The guidewire passage 232 alsoextends through the body section 230 to a distal opening 234 spaced fromthe sideport. The catheter body also defines a conduit 240 fortransmitting fluid from outside the subject through the catheter body212 into an interior of the catheter balloon once the balloon 214 ispositioned relative to a treatment region such as in bridging relationto a lesion L within the blood vessel. In the region of the catheterbody bounded by the balloon the body has an opening 242 that fills theballoon 214 with fluid that travels the length of the catheter throughthe passage 240.

The catheter depicted in FIGS. 5 and 5A is a perfusion catheter. Aguidewire is inserted into the opening 234, through the passageway 232and out the sideport 220. The balloon 214 is positioned within thesubject blood vessel and then a fluid is injected through the passageway240 from a fitting 250 having a center passage 252 bound by a threadedcoupling 254 at the extreme proximal end of the catheter 210.

In the embodiment illustrated in FIG. 5A the passageway 216 that extendsthrough the balloon allows blood to flow into an opening 262 in a thecatheter body, flow through the generally cylindrical passageway 216 andexit the catheter body. Plural openings 263 in a ramp portion 264 of thebody allow blood that enters the passage 216 to exit from the catheterbody at a location distal to the balloon. Additional side openings 266that extend through the walls of the catheter body also allow blood toexit the catheter at a point distal to the balloon 214. The openings 263in the ramp are small enough to prevent the guidewire from entering thepassageway 216 as the catheter is pushed over the guidewire.

The tube that defines the passageway 216 supports a short annularextension 270 that is fused to the catheter body. The extension isconstructed from a low durometer radiopaque polymer that does not damagethe blood vessel when the catheter is withdrawn back into the guidecatheter. To aid the physician in keeping track of the position of theballoon either embodiment of the invention can include a radiopaquemarker. Such a marker 272 is schematically depicted in FIG. 5A.

Each of the embodiments described above has a cutout portion thatdefines a side port for insertion of a guidewire at a point distal tothe balloon. But for use of a stiffening rod 280 at the region of thesideports each of the catheters would be weakened and made too flexibleat the region of the side port. The stiffening rod 280 is attached tothe body of the catheter by placing the rod 280 in the passageway 140for the embodiment of FIGS. 2, 2A, 3, and 4 or in the passageway 240 forthe embodiment of FIGS. 5, 5A, and 6 and fusing the rod to the catheterbody when the distal end of the catheter is fused into a tapered distaltip.

While the present invention is described above in considerableparticularity, it is to be understand that those of ordinary skill inthe art may be able to make certain additions or modifications to, ordeletions from, the specific embodiments described herein, withoutdeparting from the spirit or the scope of the invention, as set forth inthe appended claims.

We claim:
 1. A method for placing a catheter within a subject bloodvessel comprising the steps of:a) providing a balloon catheter having aninflatable balloon at a distal location and having a catheter body thatdefines a guidewire passage extending through the catheter body from adistal opening at the balloon catheter's distal tip to a sideport thatopens outwardly from a sidewall of the catheter body into the bloodvessel at a catheter body location between the balloon and the distalopening; b) inserting a guide catheter into a subject and positioningthe guide catheter relative a treatment region of a subject bloodvessel; c) inserting a flexible guidewire into a proximal end of theguide catheter and pushing the guidewire through the guide catheter bodyand out the distal end of the guide catheter to bring the guidewire intoposition relative to the treatment region; d) pushing the distal openingof the balloon catheter over a proximal end of the guidewire and routingthe proximal end of the guidewire out the sideport and then pushing theballoon catheter into the subject along the guidewire to position theballoon at a treatment region within a subject vessel; and e) inflatingthe balloon to bring outer wall portions of the balloon into contactwith inner wall portions of the subject blood vessel, wherein theballoon catheter further defines an elongated passageway extending froma proximal end of the catheter to the sideport that allows over-the-wireinsertion of the balloon catheter into the subject and comprising theadditional step of inserting a stiffening mandrel into the elongatedpassageway until an end of the passageway is blocked by the mandrel toavoid insertion of the proximal end of the guidewire into the elongatedpassageway.
 2. A catheter for placement within a subject comprising:anelongated catheter body and an inflatable catheter balloon coupled tothe elongated catheter body for placement within the subject relative toa treatment region of a vascular system of the subject, the catheterbody defining an inflation lumen for transmitting fluid from outside thesubject through the catheter body into an interior of the catheterballoon once the catheter balloon is positioned relative to thetreatment region, the catheter body having a distal end and defining adistal opening near the distal end, the catheter body also defining alongitudinal passageway that extends from outside the subject throughthe catheter balloon to the distal opening near the distal end of thecatheter body, the catheter body having a location spaced from thedistal opening and distal to the catheter balloon, the catheter bodyfurther defining a sideport that opens outwardly from the longitudinalpassageway at the location spaced from the distal opening and distal tothe catheter balloon such that the catheter body defines a guidewirepassage through the distal opening into the longitudinal passageway andout of the longitudinal passageway through the sideport for insertion ofa guidewire; and a removable elongated stiffening mandrel adapted toextend from outside the subject and through the longitudinal passagewayto a position proximal to the sideport such that the mandrel preventsfurther insertion of the guidewire into the longitudinal passagewayproximal to the sideport thereby causing the inserted guidewire to exitthrough the sideport.
 3. The catheter of claim 2, wherein the catheterbody is adapted for over-the-wire insertion of the catheter body intothe subject by insertion of a guidewire through the distal opening andinto the longitudinal passageway when the mandrel is removed from thelongitudinal passageway.
 4. The catheter of claim 2, additionallycomprising a stiffening rod connected to the catheter body that adds astiffness to the catheter at the sideport.
 5. The catheter of claim 2,further comprising a connector attached to the catheter body outside thesubject and additionally comprising a fitting attached to a proximal endof the stiffening mandrel for positioning the mandrel in thelongitudinal passageway as the fitting abuts the connector.
 6. Thecatheter of claim 2, in combination with:a guiding catheter forinsertion into the vascular system of the subject, the guidewire forinsertion into the guiding catheter to a position relative to thetreatment region of the subject and for insertion through the guidewirepassage of the catheter body to guide the catheter body to a positionrelative to the treatment region; and a source of inflation fluid thatcan be coupled to the catheter body for injecting fluid through theinflation lumen in the catheter body to inflate the catheter balloon.